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Thread: Inheriting Array() Properties

  1. #1
    Join Date
    May 2013
    Posts
    2

    Inheriting Array() Properties

    Hello All,

    I am trying to create an object to holds random variables. These variables are randomly generated using the Math.random() function. I would like to have an object that has a lot of the Array() properties so that everytime the user clicks a button (or some sort of event happens), a new variable is pushed into the Object. So far this is what I am thinking the code should look like. NOTE [Don't worry about the randomizing side of it, because I know that part works, I am simply looking for advice on the Array inheritance so that every index on the object has all the properties and member functions]:

    Code:
    // function to randomly generate a number NOT THE PROBLEM
    
    function myrand(min,max,inc)
    {
        var lo=min-inc;
        var range=(max-lo)/inc;
        var A=inc*(Math.ceil(Math.random()*range+lo/inc));
        return A;
    }
    
    // Object to store random variables, THIS IS THE PROBLEM
    
    function randVar()
    {
        // Inheritance
        this.push = function () {
            Array.prototype.push.apply(this,arguments);
        }
    }
    
    // Member Functions 
    
    randVar.prototype.setName = function(name){  // allows user to set the variables name
        this.name = name;                            
    }
    
    randVar.prototype.setMinMaxInc = function(min, max, inc) 
    { // sets the minimum and maximum values the variable can range from, inc is the increment                                                                             
        this.min = min;                                                      
        this.max = max;
        this.inc = inc;
    }
    
    randVar.prototype.getRandNum = function()  // calculates and returns the random variable
    {
        this.num = myrand(this.min, this.max, this.inc); // function was created above
        return this.num;
    }
    
    // Ideally in use:
    
    var r = new randVar();
    
    r.push();
    r[0].setName("First Variable");
    r[0].setMinMaxInc(1,10,1);
    r[0].getRandNum(); // returns a random number between 1 and 10 in increments of 1
    
    r.push();
    r[1].setName("Second Variable");
    r[1].setMinMaxInc(11,20,2);
    r[1].getRandNum(); // returns a random number between 11 and 20 in increments of 2
    I know this code is not correct. However I am looking for some advice. Hopefully what I am looking for makes sense for it will greatly simplify my project. Thanks!

    Cheers,
    JSHARP

  2. #2
    Join Date
    Feb 2003
    Location
    Michigan, USA
    Posts
    5,755
    If you want a more declarative way, plus the support of inheriting class level properties and mixins (ala Ruby), use this:

    https://github.com/gburghardt/JsLib/...es/function.js

    Now you can use:

    Code:
    var Mixin1 = {
      prototype: {
        foobar: function() {}
      }
    };
    
    var Mixin2 = {
      self: {
        baz: function() {}
      }
    };
    
    RandVar = Array.extend({
      
      // fake multiple inheritance
      includes: [Mixin1, Mixin2],
    
      self: {
        // class methods go here
        bar: function() {}
      },
    
      prototype: {
        initialize: function() {
          // constructor code goes here
        },
    
        // instance methods go here
        foo: function() {}
      }
    });
    
    var rand = new RandVar();
    rand.push(1);
    
    rand instanceof RandVar; // true
    rand instanceof Array // true
    rand instanceof Object // true
    rand.constructor === RandVar; // true
    
    rand.foo(); // from "class" definition
    rand.foobar(); // from Mixin1
    
    RandVar.bar(); // from "class" definition
    RandVar.baz(); // from Mixin2
    For more information on how to use this, consult the Jasmine specs:

    https://github.com/gburghardt/JsLib/...nction_spec.js

  3. #3
    Join Date
    May 2013
    Posts
    2
    Thanks! That helps a lot.

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